CNES projects library

January 17, 2024

Lisa

LISA (Laser Interferometer Space Antenna) is an international mission led by ESA to detect gravitational waves from the most violent events in the universe.

The LISA project is setting out to detect gravitational waves with three satellites trailing Earth in its orbit around the Sun to form a giant laser interferometer in which each “arm” of the triangle will be 2.5 million kilometres long.

Predicted by Albert Einstein’s theory of general relativity in 1916, gravitational waves were observed for the first time—from Earth—in 2015. They are distant echoes of the most violent events in the cosmos.

LISA will consist of three satellites following the Earth around the Sun, trailing about 50 million kilometres behind the planet. Each satellite will be located at the point of an equilateral triangle 2.5 million kilometres on a side, forming a giant optical interferometer inclined at an angle of 60° to the plane of Earth’s orbit.

The satellites will be linked in pairs by identical and synchronized laser beams to measure any relative movements between free-fall test masses inside each instrument. These test masses are in an environment isolated from external disturbances—solar wind, parasitic forces etc.—and will reveal any infinitesimal distortions in space-time. The expected level of sensitivity is 10 picometres over a million kilometres, in a low-frequency range that the ground-based LIGO (Laser Interferometer Gravitational-wave Observatory) and Virgo facilities are unable to measure.

To accomplish this technological feat, CNES is working within the LISA consortium to federate a community of French research laboratories that will be making a major contribution to the mission. LISA-France is expected to be tasked with integrating and testing the instruments, as well as with designing and developing the science ground segment. This work will involve a big contribution to performance simulations and modelling, and to prepare for scientific exploitation of data from the mission.

Between 2015 and 2017, ESA launched and operated a first technology demonstration mission called LISA-Pathfinder. The excellent results validate the key building blocks of the future LISA mission, notably the ability to maintain a test mass in purely gravitational free fall and obtain highly precise interferometric measurements inside the instrument.